app config file, incorporating postgres for data mgmt

config.py

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+import os, json
+import psycopg2
+
+class Config:
+    # store all user input
+    def __init__(self):
+        self.data_path = None
+        self.pg_config = None
+        self.sort_by_match_strength = False
+
+    def run(self):
+        """Completes new config process or uses an existing one. Dumps new data into a JSON file if it is generated, and returns either an old instance of `Config` or the new one as `self`"""
+        if os.path.exists("./config.json"):
+            prev_config = self.handle_prev_config()
+            if prev_config is not None:
+                return prev_config
+            else:
+                self.get_data_path()
+                self.set_pg_config()
+                self.output_formatting()
+                with open("./config.json", "w") as outfile:
+                    json.dump(self.__encode(), outfile)
+                return self
+        else:
+            self.get_data_path()
+            self.set_pg_config()
+            self.output_formatting()
+            with open("./config.json", "w") as outfile:
+                json.dump(self.__encode(), outfile)
+            return self
+
+    # if a config file already exists, offer to use it instead
+    def handle_prev_config(self):
+        """Receives user input and attempts to locate existing config file."""
+        response_for_prev_config = input("Use existing configuration file? y/n " ).lower()
+        
+        if response_for_prev_config == "y":
+            prev_data: Config = open("./config.json")
+            prev_data = json.load(prev_data)
+            return prev_data
+        elif response_for_prev_config == "n":
+            return None
+        else:
+            print("Invalid response.")
+            self.handle_prev_config()
+
+    def get_data_path(self):
+        """Locates a valid directory from user input and stores it in Config state as `self.data_path`."""
+        data_path = input("Provide the location of the directory where we can find your photos: ")
+
+        if not os.path.exists(data_path):
+            print("We didn't find a directory by this name.")
+            self.data_path = self.get_data_path()
+        else:
+            print("Got it!")
+            self.data_path = data_path
+
+    def set_pg_config(self):
+        """Determine if data should be associated with a PostgreSQL instance, and, if so, record the required connection info"""
+        elect_for_pg = input("Connect this program to a PostgreSQL instance? y/n ").lower()
+        if elect_for_pg == "y":
+            self.pg_config = {}
+
+            print("Please provide the relevant connection info. This sensitive information will only be recorded locally on your own machine.")
+            dbname = input("Provide the DB name: ")
+            user = input("Provide the username: ")
+            password = input("Provide the password: ")
+
+            print("The following details are optional and may be skipped if connecting to a local instance")
+            host = input("Provide the host address: ")
+            port = input("Provide the port connection number: ")
+
+            print("Testing connection:")
+
+            try:
+                dsn = f"dbname={dbname} user={user} password={password}"
+                if host:
+                    dsn = dsn + host
+
+                if port:
+                    dsn = dsn + port
+
+                conn = psycopg2.connect(f"dbname={dbname} user={user} password={password}")
+                conn.close()
+
+                print("Connection successful!")
+                self.pg_config['dsn'] = dsn
+            except psycopg2.Error as e:
+                print("There was an error connecting: ")
+                print(e)
+                self.set_pg_config()
+
+        elif elect_for_pg == "n":
+            pass
+        else:
+            print("Invalid response.")
+            self.set_pg_config()
+
+    def output_formatting(self):
+        sort_by_match_strength = input("Sort all files by match strength, or mix all matches together? sort/mix ").lower()
+        if sort_by_match_strength == "sort":
+            self.sort_by_match_strength = True
+        elif sort_by_match_strength == "mix":
+            self.sort_by_match_strength = False
+        else:
+            print("Invalid response.")
+            self.output_formatting()
+
+    def __encode(self):
+        return json.dumps(self, default=lambda x: x.__dict__)
+
+new_config = Config()
+new_config.run()